Routing methods, systems, and computer program products

1. A method, comprising:

at a first node:

receiving first information associated with a path from the first node to a second node; and

based on the first information, generating a set of one or more segment identifiers at least one of which is:

in an address space having a span in a current region in which the first node resides,

configured for use in identifying a next region,

representative of at least one network path segment, and

includes a value that is identical to that of another segment identifier of the set that is representative of another network path segment that is different from the at least one network path segment.

2. The method of claim 1 , wherein a first segment identifier of the set of one or more segment identifiers identifies a node.

3. The method of claim 2 , wherein a second segment identifier of the set of one or more segment identifiers identifies a hop.

4. The method of claim 1 , wherein a first segment identifier of the set of one or more segment identifiers is globally unique in the current region.

5. The method of claim 1 , further comprising: determining whether to use a node or a hop to encode a path between two nodes of the path.

6. The method of claim 1 , wherein the path comprises a plurality of nodes between the first node and the second node.

7. The method of claim 1 , wherein the first information identifies a second path, and the generating comprises generating a second set of one or more segment identifiers, and combining the set of one or more segment identifiers and the second set of one or more segment identifiers.

8. The method of claim 7 , wherein at least one of the first set of one or more segment identifiers or the second set of one or more segment identifiers is represented by a symbolic identifier.

9. The method of claim 1 , wherein the generating comprises calculating a reverse path from the second node towards the first node.

10. An apparatus, comprising:

at least one processor; and

memory in communication with the at least one processor, the memory having one or more programs stored therein;

wherein the one or more programs are stored in the memory and configured to be executed by the at least one processor, the one or more programs including instructions to:

receive first information associated with a path from a first node to a second node; and

generate a set of one or more segment identifiers at least one of which is:

in an address space having a span in a current region in which the first node resides,

configured for use in identifying a next region,

representative of at least one network path segment, and

includes a value that is identical to that of another segment identifier of the set that is representative of another network path segment that is different from the at least one network path segment.

11. The apparatus of claim 10 , wherein the apparatus is configured such that a first segment identifier of the set of one or more segment identifiers identifies a node.

12. The apparatus of claim 11 , wherein the apparatus is configured such that a second segment identifier of the set of one or more segment identifiers identifies a hop.

13. The apparatus of claim 10 , wherein the apparatus is configured such that the first node includes an ingress node for the region.

14. The apparatus of claim 10 , wherein the apparatus is configured such that the second node includes an egress node for the region.

15. The apparatus of claim 10 , wherein the apparatus is configured to determine whether to use a node or a hop to encode a path between two nodes of the path.

16. The apparatus of claim 10 , wherein the apparatus is configured such that the first information identifies a second path, and generating the set of one or more segment identifiers comprises generating a second set of one or more segment identifiers, and combining set of one or more segment identifiers and the second set of one or more segment identifiers.

17. The apparatus of claim 10 , wherein the apparatus is configured such that generating the set of one or more segment identifiers comprises calculating a reverse path from the second node towards the first node.